Heuer (pronounced hoyer) built several thousand of these in contract batches from 1967-1981 for the West German military, replacing Hanhart and other makers. They were issued to aid in combat and navigation timing. 3H and T tritium luminous paint symbols used during the 1960's, no longer legally needed but the proofs are sometimes used to make a watch look more militant. Similar Sinn 156 were available after production ended on the Swiss Heuer. Different looking Tutima, among others, were issued that used the same automatic movement as the Sinn. German Sinn still makes cases and "15 30 45" bezels that are identical to original. Mine wasn't issued to a West German soldier but it was made to 1960's NATO Mil-Spec regardless of when it was put together. Band: 6645-12-145-6415 Bund, 4 screw back: BUNDESWEHR 6645-12-146-3774. Heuer-Leonidas S.A. Biel, Switzerland (inside case). Based on the 1916 caliber 23, Valjoux 230: 17 jewels, manual wind, 36 hour power reserve, 18,000 bph, incabloc shock, plastic crystal, water resist 3 ATM. I've noticed the bridge designs interchange between various older Valjoux components but am not qualified to comment as to why, doesn't seem to be by type or date. China makes good unlicensed copies of the Heuer/Sinn military case and strap that are visually similar to the European made, movements themselves can't be cheaply faked. Link to a scanned tech manual.
